I used Minwax Sanding Sealer for years and painted over it with no issues. Krylon, Rusto/2X, Valspar. I started to wonder over the years why I even used the stuff. It did help with assisting with a smoother finish, but lacked in strengthening the balsa. Then I discovered the water based sanding sealers. Deft and Minwax both offer these and they give the same sanding results as the other, but make the balsa more rigid. Easy clean-up is a blessing here also. Neither of them were meant as balsa fillers, in case that is where your thinking was headed.